Electrical- contactor



w. w. ANDERSON ET AL 2,844,684

July 22, 1958A ELECTRICALCONTACTOR 2 Sheets-Sheet l FIG.;

Filed Jan. 7, 1955 FIG.2

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July 22, 1958 w. w. ANDERSON ET AL 2,844,634

ELECTRICAL CONTACTOR 2 Sheets-Sheet 2 Filed Jan. 7, 1955 INVENTORSWARREN w. ANDERSON DONALD J. HAMMERAND E A QN l nite States PatentOiiice y 2,844,684 yPatented July 22, 1958 ELECTRICAL CNTACTORApplication January 7, 1955, Serial No.v 480,504

' 6 cintas. (ci. zoo-a3) The present invention relates to circuit makingand breaking apparatus and more particularly to a novel form ofcontactor assembly which will be found useful in connection withelectrical circuits associated with a large variety of equipment,particularly electrical equipment involving a reversible motor circuitor a plurality of individual circuits.

rl'he invention has been illustrated herein in the form of anelectromagnetically operated vcontactor assembly having dual pairs ofcontacts capable of being alternatively opened and closed toalternatively establish or energize a pair of work circuits eachcontaining a suitable load, as for example the field windings of areversible motor. The invention is however susceptible to modificationand, if desired, the contactor may be designed for single or pluralworking circuit operations.

lt is among the principal objects ofthe present invention to provide anovel contactor assembly of the type briefly outlined above which isquick-releasing with respect to either pair of contacts so that theswitching of circuits may take place rapidly, thus avoiding undue arcingat the contact points.

Another vand important object is to provide such a contactor assemblyfor dual circuit control which requires but a small amount of lowvoltage current consumption'for its operation. A similar and relatedobject is to provide a dual circuit contactor which will operate tomaintain one of the two circuits involved closed indefinitely with nocurrent consumption whatsoever and to maintain the other circuit closedunder the influence of a current of low voltage.

Yet another object of the invention is to provide a contactor assemblyof this type in which a permanent magnet and an electromagnet may beemployed without requiring a reversal of the current through theelectromagnet, as is usual in the prior art, to make the permanentmagnet effective.

T he provision of a contactor assembly vwhich is rugged and durable andwhich therefore is possessed of a comparatively long life; one which iscomprised of a minimum number of movingparts and which therefore isunlikely to get out of order; one which is extremely compact so that itwill occupy `but small space; one which may readily be assembled anddisassembled for purposes of inspection, replacement or repair; onewhich is comprised largely of metal stampings and which may there forebe manufactured at a low cost, and one which otherwise is well adaptedto perform the services required of it, are further desirable featuresthat have been borne in mind in the production and development of thepresent invention.

lnfthe accompanying two sheets of drawings forming a part of thisspecification, a preferred embodiment of the invention has been shown.

ln these drawings:

Fig. l isa top plan View of a contactor assembly constructedinaccordance with the principles of the invention;

construction.

Fig. 2 is a sectional view taken substantially along the line 2 2 ofFig. 1;

Fig. 3 is a sectional View 'taken substantially along the yline 3`3 ofFig. l;

Fig. 4 is'a `side elevational View of the structure shown in Fig. vl;and

@Fig 5 is a circuit diagram showing the contactor assembly operativelydisposed in an exemplary work circuit.

Referring now'to `the drawings in detail, the contactor yassemblyinvolves in its general organization a base plate 410 of a suitableelectrical linsulating material, the plate serving as a support forfallof the operative contactor elements. As shown in Fig. 3, "the base plate10 has mounted thereon at its opposite ends first and second contactgroups 11 and 12 which are preferably of identical A magnetic yoke inthe form of a at plate 13 of magnetizable material such as soft iron ispositioned in face-to-face contact with the base plate 10 and aplurality of clamping-screws 14 pass through the yoke 13 and arethreaded in a laterally turned ange 15 provided on an armature support16. The armature supporting end of the support l16 is formed ywith apair of spaced upstanding lugs 17. A -rnagnetizable metallic armature 18in the 'form of a `rectangular plate is movably positioned to overlapboth magnets so as to be within the magnetic intiuence thereof. rl"hesaid armature is preferably supported medially of its ends on the upperedge of the support 16. The edges yof the armature 18 are "slotted as at20 (Fig. '3), with the slots registering with 'the lugs 1'7. Retainingpins 21 extend through the lugs 17 to retain the armature in position onthe support 16 while permitting slight rocking 'movement of the armaturethereon for purposes that will appear presently.

The opposite ends of the `armature have supported thereon rst and secondbrushassemblies 22 and 23 respec-tively, including brush elements proper50, 55 delsigned for cooperation with'the respective contact groups 11and 12.

A permanent magnet 25-is composed of extremely hard metal, for exampleAlnico. armature support 16 and contact group 11 and is secured inposition on the lmagnetic yoke '13 by a screw 26 passingfthrough thelatter land threaded into a plug or core 27 embedded in the body of themagnet 2S. The core 27 'is composed of softer metal to facilitate theuse of the usual equipment for forming the internal threads. An

Iel'ectromagnet Sli/having -a core 31 and a winding 32`isfcllisposedbetween the armature support 16 and theA contact group 12and is secured in position on the yoke 16 by a screw 33 ipassing through'the yoke and threaded into the .core 31. The upper faces of thepermanent magnet y25 land core 3'1are substantially at and horizontaland, as a consequence, the armature 18 is of obtuse `Vshapedin'longitudinal cross section in order that, upon rocking movementsthereof, the underneath face of the armature may move into face-to-face`magnetic engagementwith these two surfaces alternately `duringoperation of the contactor assembly.

The contact groups 11 and 12 being of similar construction, it isthought that a description of one will suice for the other. The contactgroup 11 is best illustrated in Fig. 2 and comprises a pair of contactelements 34san'd 35, thel latter element being in the form of anL-shaped stamping, preferably of copper which is supported `on yanLesha'ped bracket 36 kand held in position :bya clamping screw 37. Acopper connector strap orbus bar 38 has one'end thereof clamped betweenthe support 36 and contact 35 and Vextends longitudinally of theassembly to a corresponding arrangement of parts including a contactelement `40 associated with the contact group v1'2.l A terminal screwand washer assembly It is disposed between the 3 39 are carried mediallyon the connector strap 38 for connection to a lead-in wire 42. Thesupport 36 is secured on the base by a clamping screw 43.

The contact 34 is generally U-shape and has an inturned foot which issupported on a separator strip 45, a clamping screw 46 serving toholdthe various parts in position. The contact 34 carries a terminal screw47 to which a lead-outwire 48 may be attached.

The brush assembly 22 which is carried at one end of the armature 18includes a brush proper 50 preferably formed of copper and operable inthe manner of a bridging contact to bridge the two contacts 34 and 35and complete the otherwise open current path extending from the lead 42to the lead 48. The brush 50 is slidably carrie-d on a post 51 which issecured by a screw 52 to an ear 53 formed on the end of the armature 18.A head 54 and seating washer 55 limit the downward movement of the brush50. A spring 56 surrounds the post 51 and normally urges the brush to anadvanced position on the post. A guide plate 51a is secured to thearmature and slidably engages the brush bar to hold the same fromrotational movement about said post 51. As will be explained later, thearmature 1S is adapted to be attracted by the permanent magnet 25 sothat it will assume the position shown in Fig. 3 wherein the brush 50engages and bridges the contacts 34 and 35 and, when in this position,the head and seating washer 54, 54a become extended so that the spring56 may force the brush 5t) into positive engagement with the contacts 34and 35.

The contact group 12, in addition to the contact element 4t?, includes asecond contact element 41, the two contacts being mounted in assembliessimilar to those shown in connection with the contacts 34 and 35 andsimilarly designated in the drawings. Likewise, the brush assembly 23includes a brush element proper 55 mounted in the assembly 23 in thesame manner that the brush 50 is mounted in the assembly 22. The spring57 of the brush assembly has a slightly greater resistance tocompressional forces than has the spring 56 for a purpose that willbecome clear presently.

As shown in Fig. l, a lead-in binding post 58 and a lead-out bindingpest 59 are mounted on the base 1l? on opposite sides of theelectromagnet 30 and are electrically connected to the magnet winding 32by Wires 60 and 61 respectively. The post 58 is adapted to be connectedthrough a preferably, but not necessarily manually operable switch Sw tothe positive side of a suitable source of low voltage current asexemplified by the battery B (Figs. 1 and 5). The terminal 59 is adaptedto be iconnected to the negative side of the battery B o1 ground.

The contactor assembly is shown in its normal position in Fig. 3 whereinthe underneath face of the armature 1d is attracted to the north pole ofthe permanent magnet 25 and makes contact with the latter so that thespring 56 is under compression. With the parts in the position shown,the brush 50 bridges the contacts 34 and 35 while the brush 55 is raisedfrom the contacts 40 and 41. In the exemplary circuit diagram shown inFig. 5, a work circuit will thus exist from the source S, through lead70, terminal 41, strap 38, contact 35, brush 50, contact 34, terminal47, lead 48, load W1 which may be one of the eld coils of a reversibleelectric motor, diagrammatically shown as a rectangle M in dotted lines,and lead 71 to the negative line.

The other iield winding W2 of the motor M is disposed in a circuitparallel to the circuit just described and, when it is desired to closethis latter circuit and open the former circuit, the switch Sw is closedmanually to establish a circuit from the positive side of the battery Bthrough lead 72, binding post 58 (Fig. 1), lead 60, winding 32 of theelectromagnet 30, lead 61, binding post 59, and leads 73 and 74 to thenegative side of the battery. Energization of the electromagnet 30 willattract the armature 18 to the south pole of the magnet core 30 to rockthe armature 13 in a clockwise direction as shown in Fig. 3 and causethe brush 55 to bridge the contacts and 41 and establish a circuitthrough the winding W2 and lead 75 to the negative line. immediatelyprior to bridging of the contacts 4@ and 41 by the brush 55, the brushwill be elevated from the contacts 34 and 35 to open the circuit throughthe winding W1.

It is to be particularly noted that with the electromagnet 30deenergized the attraction of the permanent magnet 25, which ispreferably formed of a nickel-ironaluminum alloy known as Alnico #5 andwhich has a high degree of residual magnetism, is suilicient to maintainthe armature 18 attracted against the yielding action of the spring 56as shown in Fig. 3. Upon energization of the electromagnet 30, amagnetic teld is set up in and around the magnet structure resulting ina flow of magnetic flux which follows generally the path indicated bythe full line arrows through the yoke 13, armature support 16, a portionof the armature 18 itself, and the core 31, as well as across the airgap 76 (Fig. 3) existing immediately prior to bridging of the contacts40 and 41. This iiow of ilux opposes the residual magnetism of thepermanent magnet 25 and bucks the normal ilux ow set up by this lattermagnet as shown by the dotted arrows on Fig. 3 so that the effectiveattractive force of the magnet 25 is materially weakened and thearmature 18 is released thereby.

It is also to be noted from an inspection of Fig. 3 that with the magnet30 deenergized and with the armature 18 elevated above the level of theupper surface of the magnet core 31, the magnet 3d has no effect uponthe armature. Since the armature is in intimate contact with the northpole of the permanent magnet 25, a subl stantial portion, if not all, ofthe armature 18 is magnetized with the strength of the magnetic elddecreasing in proportion to the distance of each increment of the ironmaterial from the pole of the magnet 25. Thus when the magnet 30 becomesenergized in such a manner as to render the upper end of the core 31opposite in polarity to the thus magnetized armature, a very strongmagnetic attraction exists between the armature 1S which at the time ofits attraction to the magnet 311 has a polarity opposed to the polarityof the adjacent end of the core 31. The phenomena just described isconducive toward a powerful pull on the armature by the magnet 3i) and aconsequent rapid shitting of the Various contacts. The pull of themagnet 3) is also assisted by the recoil of spring 56 which is somewhatstronger than the spring 57 and gives an initial impetus to the armaturetending to cause it to rock in a clockwise direction with suflicientmomentum that the spring 57 will become compressed to a suflicientdegree to permit the armature to come within the sphere of magneticinfluence of the electromagnet 30. Consequently, the armature 1S may bemoved out of the range of influence of the permanent magnet by a minimumexertion of the electromagnet.

When it is desired to restore the original circuit through contacts 34,35 to open the contacts 4t), 41, it is merely necessary to open theswitch Sw to deenergize the electro magnet 30. The spring 57, havingbeen under compression, will recoil to give an impetus to the armature18 to rock it in a counter-clockwise direction suiciently to bring itinto the range of the magnetic iniuence of the permanent magnet 25.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings or described in this specificationexcept insofar as such limitations appear in the claims. It will beo-bvious that various changes in the details of construction may beresorted to without departing from the spirit of the invention. It willbe also understood that the size of the unit and the character of theloads W1 and W2, which are not necessarily the eld windings of areversible motor bination, a pair of spaced contacts, a permanent magnethaving a relatively high degree of residual magnetism, an electromagnethaving a iixed core separate from said permanent magnet and in oppositepolarity thereto whose polarity is reversed with respect to the polarityof the permanent magnet; means defining a magnetic yoke common lto bothmagnets including a base plate engaging said permanent magnet and saidcore, a magnetizable armature positioned to overlap both magnets andhaving one end engageable with the permanent magnet and its other endengageable with the electromagnet; said armature when in one extremeposition being disposed within the magnetic field of the permanentmagnet and operative to establish an electrical circuit through saidcontacts, and an armature support connecting said base and the armaturemedially of the latter and serving as a common path for the magneticflux of both magnets, whereby the energization of the electromagnet setsup magnetic flux in said common yoke in opposition to the residualmagnetism of said permanent magnet and effects release of said armaturefor movement thereof out of the magnetic iield of said permanent magnet.

2. An electrical contactor assembly as dened in claim 1 characterized inthat said armature support is iixed and is comprised of magneticmaterial and is in direct contact with said magnetic yoke at one end andis pivoted to said armature medially of the latter at its other end,whereby when the latter is attracted to the permanent magnet a closedflux path exists through the yoke, permanent magnet, armature andsupport, and whereby when the armature is attracted to the electromagneta closed ilux path exists through the yoke, armature support, armatureand electromagnet core.

3. An electrical contactor assembly comprising in combination, amagnetic yoke, an armature support formed of magnetic material extendingmedially from said yoke, a permanent magnet having its body extendingfrom said yoke on one side of the support, an electromagnet having acore separate from said permanent magnet and in opposite polaritythereto extending from said yoke on the other side of said support, anarmature common to said permanent magnet and electromagnet pivotedmedially of its ends to said armature support for limited rockingmovement between one extreme position wherein one end thereof isdisposed within the magnetic eld of the permanent magnet and anotherextreme position wherein the other end thereof is disposed within themagnetic eld of the electromagnet when the latter is energized,electrical contact structure at one end of said armature and movablewith the latter, said yoke, armature support, armature and coreconstituting a closed ux path for the electromagnet when the latter isenergized, said yoke, armature support, armature and magnet bodyconstituting a closed flux path for the permanent magnet when thearmature is attracted thereto, and means for supplying a predeterminedcurrent flow to said electromagnet in a direction to set up a ow of uxin said closed path of the electromagnet in opposition to the flow offlux in said closed path of the permanent magnet.

4. An electrical contactor assembly comprising, in combination, amagnetic yoke, an armature support formed of magnetic material extendingmedially of said yoke, a permanent magnet having its body extending fromsaid yoke on one side of said support, an electromagnet having a coreextending from said yoke on the other side of said support, an armaturecommon to said permanent magnet and electromagnet pivoted medially ofits ends to said armature support for limited rocking movement betweenone extreme position wherein one end thereof is disposed within themagnetic field of the permanent mag- ,6 net and another extreme whereinthe other end thereof is disposed within the magnetic iield of theelectromagnet when the latter is energized, electrical contact structureat one end of said armature and movable with the latter, said yoke,armature support, armature and core constituting a closed iiux path forthe electromagnet when the latter is energized, said yoke, armaturesupport, armature and magnet body constituting a closed iux path for thepermanent magnet when the armature is attracted thereto, means forapplying a predetermined current flow to said electromagnet in adirection to set up a iiow of iiux in said closed path of theelectromagnet in opposition to the flow of iiux in said closed path ofthe permanent magnet, spring means operable when said armature is insaid one extreme position to bias the armature away from said extremeposition, and spring means likewise operable when the armature is in itsother extreme position to bias the armature away from said latterextreme position, said irst mentioned spring means normally exerting abiasing eiiect on said armature less than the attractive force of saidpermanent magnet and said second spring means normally exerting abiasing effect on said armature less than the attractive force of saidelectromagnet when said predetermined iiow of current is suppliedthereto.

5. In a contactor assembly, a iirst pair of fixed spaced contacts, asecond pair of iixed spaced contacts remote from said first pair ofcontacts, an armature support formed of magnetic material disposedbetween said pairs of contacts, an armature pivoted to said supportmedially of its ends `for limited rocking movement thereon, tirst andsecond brush members mounted on said armature at the opposite endsthereof respectively, said armature being movable between one extremeposition wherein said iirst brush member electrically bridges said iirstpair oi contacts and another extreme position wherein said second brushmember electrically bridges said second pair of contacts, a permanentmagnet positioned between said support and the first pair of contactsand operable upon one end of the armature, an electromagnet positionedbetween the support and the second pair of contacts and likewiseoperable upon the other end of the armature, a magnetic yoke bridgingthe core of the electromagnet, the support, and the body of thepermanent magnet and positioned so that when a predetermined ow ofunidirectional current is passed through the electromagnet, flux is setup in said yoke in opposition to the residual magnetism of the permanentmagnet, a connector strap connecting one contact of the tirst pair ofcontacts with one contact of the second pair of contacts, and pluralspring means operable when said armature is in either of its extremepositions for biasing the same away from said position.

6. In a contactor assembly, the combination set forth in claim 5 whereinthe spring means which is operable to bias the armature from the extremeposition it assumes when attracted by said electromagnet is of greaterforce than the other spring means.l

References Cited in the tile of this patent UNITED STATES PATENTS UNITEDSTATES PATENT QEETCE CERTIFICATE 0F CORRECTUN Patent Noo 2,8..,68n July22, 1958 Warren W., Anderson et el It is hereby certified that errorappears in the printed specification of the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3, 2*, for "leedein wire 4,2," read e@ leedein Wire 7G., me; line14., for-Head J+2 read m. lead '70 me; column 55 line 9, after "magnet"strike out "and in opposite polarity thereto Signed end sealed this llthday of November 1958,

(SEEE) Attest:

KARL E@ v.M {LNE ROBERT C. WATSON Attesting Ocer Commissioner of PatentsUNITED STATES PATENT oEETcE CETIFCATE @F CORREC'HGN Patent No.,2,8A..,68,L July 221 195g Warren W, Anderson et el It is herebycertified that error appears in the printed specification of the abovenumbered patent requiring correction and that the said Letters Patentshould read es corrected below.

Column 3, line 2, for "leed-11 wire 42" read me leedein Wire '70.. de;line 14, forlead' 42 read m, lead '70 ne; column 5,. line 9, after"magnet" strike out nand in opposite polarity thereto" 0 Signed endsealed this 11th dey of November 1958o (SEEE) Attest:

KARL EL, 'AXLINE ROBERT C. WATSON Attesting Ocer Commissioner of Patents

